1.Hydralics is the study of pressure in liquids.

2. pneumatic is the study of pressure in gasses

3. The caterpillar is a hydraulic device

The cannon is a hydraulic device

The reed drill is a hydraulic device

The DBT is a hydraulic device

4. The pipe organ is a pneumatic device

The grinder is a pneumatic device

The sander is a pneumatic device

The torque wrench is a pneumatic device

5. Transport an aplied force through a liquid to move something else by means of pressure.

6. Gas transmits a force exerted on the gas in an enclosed space.

7. The main diference is one uses liquid to create pressure and the other uses gas to create pressure.

Pictures from google images and video from youtube